First, answering the general question, I agree with Gerry: this seems like a perfect case for flagging for moderator attention.
Now, specifically in this case: I think the issue has been dealt in a very efficient and clean fashion. People pointed out why posting pictures instead of MathJax is a bad idea, and the user agreed after some while. However, I think it is worth pointing out that while the OP was being stubborn, he was not being blindly stubborn (at least to me). He had a point: namely, if the only advantage of using MathJax instead of images is "searchability", then the fact that he put the formula in the title should cover that (the aesthetical argument is also a little subjective and, although obvious for us, may be dismissed by a new user/by a user who doesn't know MathJax). The degree of validity of this point is questionable, sure, but he had an argument, and not a tantrum of the sort "Don't edit my question. I don't like it". Luckily people were quick to point out several other reasons, and he acknowledged them.
As a last point I would like to touch, I don't know if I agree that the main reason for preferring MathJax is searchability. The reason for this is that I personally never search for a question/answer using formulas. The times I tried, it was very ineffective. The points raised by Jyrki and also the point raised by rob that "it is easier to edit" (most of them are not in the discussion link you provided) seem to be closer to the reality and to the practical benefits.